Each day a different image or photograph is featured, with an
accompanying caption, which deals with various topics in Earth Science.

Light Pollution

Even though Mauna Kea is one of the finest dark sites for astronomy in the world, this long exposure phtotgraph reveals both artificial and natural sources of light pollution not readily visible with the naked eye. Light pollution of the night sky is an important issue for professional and amateur astronomers alike. On this two hour exposure taken from the summit of Mauna Kea, many artificial light sources are evident. In the center of the image, 200 miles (320 km) distant, is the sky glow from the city of Honolulu. Glow from towns on the island of Maui is also visible, as are lights from the Big Island (Hawaii) town of Waimea. In addition, faintly greenish natural sky glow is also visible among the star trails (top of image).